does anyone know an aftermarket tach 3 3/8 tachometer that would work with a jaguar v12? i want to make a new in dash cluster because my current speedometer doesnt work, and i want a dash with more gauges

 

im working on the same project. im using polished aluminum sheet, and autometers.

 

I think I remember reading somewhere that the tach for the v12 with a marelli ignition is a 6 cyl tach. Since the ignition system has 2 coils and is basically 2 six cyl systems merged together, it just reads off of one of the coils. Maybe it was in the "experience" book I read it.

howlinowl

 

Spot on - This is because the Marelli has one coil for each bank of 6 as apposed to the Lucas that even though it has 2 coils both coils run 12 cylinders.

There are 2 ways around this either find a Tacho that supports 12 cylinders???? or use a timing circuit to halve the number of pulses and use a 6 cylinder tacho. I'll have a think about the circuit and get back to you. Should be able to do it with a 555 timer.

 

That would be great! Im looking to use an aftermatarket cluster in the stock housing with a custom mounting interface

 

are you replacing the whole dash or just the cluster

 

Ok easiest way would be to find a KIT for a 555 timer frequency divider, could also be called a monostable vibrator.

I have attached a circuit I borrowed from the WWW. You could use a trim pot for R1 that will allow you calibrate your tacho. The V12 signal is approx 12MHz at 6500rpm so C1 and R1 would need to be sized for this frequency.

Or you could try these out they say they work with almost any engine swap combination.

Dakota Digital Universal Tachometer Signal Interfaces - SummitRacing.com

 

im doing the gauge cluster, as well as replacing the wood panels.

 

Let me know what it looks like m90, ive seen them but i cant currently find a picture